Articulated Tug Barge (ATB)

An articulated tug-barge (ATB) is a tug-and-barge combination joined by a mechanical connection that hinges in the fore-and-aft (pitch) plane while locking the tug rigidly in yaw and roll. The tug sits in a deep notch in the barge stern and engages a pin connector such as the Intercon or Bludworth system, whose toothed rams mate with a vertical rack in the notch walls. The hinge lets the unit work a seaway better than a rigid integrated tug-barge, while one tug crew moves cargo that would otherwise need a self-propelled ship. ATBs dominate US coastwise petroleum and asphalt trades because they crew and regulate as a tug, not as a tanker.